Compress the top bezel a bit with your fingers (maybe hold the ipod in one hand but with the fingers at the top and bottom, instead of on the sides). Try to operate the Hold button. Does it work? If not, you may need to pop off the top bezel (it is held in with a mild adhesive - see the Step-by-Step Guides for pictures and tools) and check that there is no glue/dirt/muck on the contacts. If you do the removal carefully, there should still be enough glue on the bottom of the bezel, so you should be able to push the bezel back in and the glue strip should hold it in place. Try the hold button again. If that does not work, I don't know what else could be wrong.